Life Cycle Assessment (5) Methane

[0:10]Okay, so I was talking about carbon dioxide equivalence. Exactly what does a carbon dioxide equivalent mean? Well, you could be talking about carbon in terms of carbon dioxide equivalence, but quite often in life cycle assessment, we're using it because we're looking at the impact of other greenhouse gases. And one of the more important of these greenhouse gases is methane. And methane can be produced from fossil resources, the natural gas we're very familiar with, or it can be produced by biological processes. So you have what's called anaerobic decay. So that's decay in the absence of oxygen. And the organisms that do this very often produce methane. Methane has got a different radiative forcing compared with carbon dioxide. And it depends on what time period you measure it over, but normally we report this in terms of what's called a global warming potential over 100 years. So that is the the foot the radiative forcing, the warming effect of methane compared with the the warming effect of carbon dioxide over a 100-year period. And if we compare these two gases, we find that methane has got a warming effect of about 25 times that of carbon dioxide. So if we had 1 kilogram of methane, that would be equivalent to 25 kg of carbon dioxide equivalence.